The invention relates to pump assemblies using plug assemblies to close the ends of piston bores and to methods for mounting plug assemblies in the bores. The pump assemblies are typically used in internal combustion engines to pressurize liquid used to actuate engine components including fuel injectors and intake and exhaust valves.
Fuel injection systems using high-pressure pumps for flowing actuating liquids are well known. The injectors include electronically controlled actuation solenoids that open a valve for an interval to permit liquid pressurized by a pump to extend a fuel plunger and inject fuel into a combustion chamber. Pumped high-pressure liquid may also actuate intake and exhaust valves and other engine components.
The pressure of the liquid is maintained by a high-pressure pump assembly, typically having a number of piston pumps with pistons reciprocated in piston bores to increase the pressure of the liquid.
The piston bores are typically drilled into the body of the pump assembly and closed at outer ends by plugs. The plugs are subject to the high outlet pressure of the pumped liquid and must engage the walls of the bores tightly to prevent leaks or pressure dislodgment. Cutting threads into the end of the bores to receive threaded plugs is undesirable as this can leave metal shavings that are difficult to remove. Metal shavings entrained in the pumped liquid can injure the pump and components actuated by the high-pressure liquid.
Therefore, there is a need for an improved bore plug assembly for closing the ends of piston bores in high-pressure pumps and for an improved method of installing plug assemblies in piston bores. The plug assembly should be easily and reliably installed without using threads or introducing shavings into the pump assembly.
The invention is a pump assembly with improved plug assemblies closing the ends of piston bores and a method of installing a plug assembly in the end of a piston bore in a high-pressure pump, such as a high-pressure pump used in modern internal combustion engines. The plug assemblies engage the bores tightly to prevent leaks and pressure dislodgment. The plug assemblies are fitted in drilled piston bores without the need to cut threads in the bores and clean shavings from the bores.
Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention.